1. Field of the Invention
The present invention relates to an orthogonal frequency division multiplexing (OFDM) demodulation apparatus, method and computer readable medium for reducing interference by a delayed wave that is longer than a guard interval.
2. Description of the Related Art
A conventional equalizer for overcoming a delayed wave that is longer than a guard interval eliminates such a delayed wave. A feedback type equalizer, for example, is used as such an equalizer (see, for instance, Jpn. Pat. Appln. KOKAI Publication No. 2004-165990).
Concerning OFDM channel estimation, in general, all points included in an effective symbol are subjected to fast Fourier transform, thereby extracting pilot subcarrier components and performing channel estimation.
However, the above demodulation apparatus does not have satisfactory delayed-wave elimination performance.
Further, since a received signal of an effective symbol period (N points) is used for channel estimation, both inter-symbol interference (interference between the present and preceding symbols) and inter-subcarrier interference occur, with the result that the accuracy of channel estimation is degraded.